1/ π’ This is an image mosaic of 18 randomly organised dots of starlight, the product of #Webb 's unaligned mirror segments all reflecting light from the same star back at Webb's secondary mirror and into #NIRCam's detectors. Thread π with a surprise at the end! 
2/ The mosaic was created by pointing the telescope at a bright, isolated star in the constellation Ursa Major known as HD 84406, chosen specifically because it's easily identifiable and not crowded by other stars of similar brightness, which helps to reduce background confusion
3/ Each dot within the mosaic is labeled by the corresponding primary mirror segment that captured it. These initial results closely match expectations and simulations.
4/ During the image capturing process that began on 2 February #Webb was repointed to 156 different positions around the predicted location of the star and generated 1,560 images using NIRCamβs 10 detectors, amounting to 54 gigabytes of raw data.
5/ The entire process lasted nearly 25 hours, but the observatory was able to locate the target star π― in each of its mirror segments within the first six hours and 16 exposures.
6/ These images were then stitched together to produce a single, large mosaic that captures the signature of each primary mirror segment in one frame. The images shown above are only a centre portion of that larger mosaic, a huge image with over 2 billion pixels.
7/ This activity determined the post-deployment alignment positions of every mirror segment, which is the critical first step in bringing the entire observatory into a functional alignment for scientific operations.
8/ What looks like a simple image of blurry starlight now becomes the foundation to align and focus the telescope in order for #Webb to deliver unprecedented views of the universe this summer. #WebbSeesFarther
9/ Over the next month or so, the team will gradually adjust the mirror segments until the 18 images become a single star βοΈβ‘οΈβοΈβ¬
οΈβοΈ
10/ Moving forward, #Webbβs images will only become clearer, more detail-laden & more intricate as its other 3 instruments arrive at their intended operating temperatures & begin capturing data. The first scientific images are expected to be delivered to the world in the summer.
11/ But wait, there's more! We also have #Webb's first "selfie" π€³ This image was created using a specialised pupil imaging lens inside of the #NIRCam instrument that was designed to take images of the primary mirror segments instead of images of space.
π· NASA
π· NASA
12. This configuration is not used during scientific operations, it's strictly for engineering & alignment purposes. The bright segment βοΈwas pointed at a bright star, while the others arenβt currently in the same alignment. Full blog here: blogs.nasa.gov/webb/2022/02/1β¦
β’ β’ β’
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